Electric lamp.



L. AJHAWKINS. ELECTRIC LAMP.

APPLICATION FILED MAY 1, 1914.

1,132,008, Patented Mar. 16, 1915.

WITNESSES INVENTOR i Maw Q-K'W I UNITED STATES PATENT ormon.

' menace a.

Specification of Letters Patent.

na'wxms, or sonnnacranr, NEW Yoax, ASSIGNOR To ennnnan unaware COMPANY, a conrom'rron or NEW roan.

*' ELECTRIC LAMP.

Patented Mar. 16, 1915.

Original application filed November 159, 1907, Serial No. 404,211. Divided and this application iiled Kay 1,

1814. Serial No. 885,722.

- To all whom it may concern:

Be it known that I,'LAURENOE A. HAW- KINS, a citizen of the United States, residing at Schenectadv,'in the county of Schenectady and State of ew York, have invented certain new and useful Improvements in Electric Lamps, of which the following is a specification.

My invention relates to electric lamps, and.

articularly to means for controlling two amps so that if one burns out the other becomes illuminated.

One feature of my invention is the provision of means for accomplishing this result without relays or moving parts.

The present application is a division of my coending application filed November 29, 190 Serial ,No. 404,211, for signal systems, issued July 7, 1914, as Patent No. 1,102,916. a

I will describe two arrangements of a paratus embodying my invention, and W111 then point out the novel features thereof in claims.

In the accompanying drawings, Figure 1 is a dia rammatic view showing one arrangement 0 apparatus embodying my invention, and Fig. 2 is a View similar to Fig. 1 but showing a modification embodying my invention.

Similar reference characters refer to similar parts in each of the views.

Referring first to Fig. 1, L and L are incandescent electric lamps connected in parallel and supplied with current from a source G which, as here shown, is a direct current enerator. The circuit for the lam s mag e opened and closed by a contact whic may be operated by any suitable means. A resistance R is included in the circuit in series with both lamps, and a second resistance R is in series with one lamp L. If lamps L and L are designed to o erate on thesame voltage, and resistance is the proper value, then when the filaments of both lamps are intact the voltage at the creases, and if the value'of resistance R is correct this voltage will be that at which the lamp is designed to operate so this lamp will then become illuminated. For example, if the voltage of generator G is 550, and if each lamp L and L is designed to o erate at 110 volts, the value of resistance should be such that when both lamps are intact the drop across this resistance is approximately 440 volts, that is, the value of this resistance should be approximatel four times the resistance of the parallel ranches comprising lamps L and L and resistance R. If the value of resistance R is approximately equal to the resistance of a 110-volt lamp, then when the drop across lamp L Wlll become ap proximately 110 volts so this lamp will then become illuminated.

It follows from the foregoing that resistance R may be in the form of a 110-volt lamp, as shown in Fig. 2, in which lamp L is substituted for the resistance R of Fig. 1.

My invention'is particularly well adapted for use in signals, such for example as signals used for railway signaling. In such cases, lamp L would e the main lamp and lamp L would be a reserve lamp which would become illuminated when lamp L burns out. It will be noted that when lamp L is burning, the current which flows through lamp L will be suflicient to keep the filament of the latter lamp hot, thus reducing the chance of breakage of this filament due to jarring or vibration.

Although I have here'shown'only two arrangements of apparatus embodying my invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims without I operate,

1 other branch the value of the first-mentioned resuch that if the lamp in the burns out the voltage at the remaining lamp will become the voltageat which the lamp is designed to operate.-

2. In combination, two electric lamps and a source of. current,.the normal voltage of each lamp being approximately one-fifth the voltage of said source, a circuit including said lamps in parallel and said source, a. resistance in series with one lamp and having a valueapproximately equa to the re,- sistance of the lamp, and a resistance in series with both lamps and of avalue approximately equal'to four times the resistance of the parallel branches.

3. In combination, three electric lamps and sistance being a source of current, a circuit including one of. said lamps in parallel with the other two It is hereby certified that Letters in the Patent Oifice.

only one lamp as long as 1915, upon the application of Laurence A. Hawkins, an improvement in Electric Lamps, were erroneously issued to Company, acorporation of New York, as

Signed and sealed this 20th day of April, A. 1)., 1915.

in series and said source, and a resistance in p 20 series with the lamps and having a value approximately equal to four times the resistance of the arallel branches. 4 L- In combination, two electric lamps and asource of current, a circuit including said lamps in parallel and said source, and resistances proportioned and arranged'to give the normal lamp voltage at the terminals of both lamps are burning and to give the normal voltage at the terminals of the other lamp if the first burns out. 3 7 Iii-testimony whereof I mysignature in presence of'two witnesses. n-TS 1* -LAURENCE A. Witnesses: BENJAMIN B. HULL,

MARGARET E. WOOLLEY.

Patent No. 1,132,008, granted March 16, of Schenectady, New York, for

General Electric Letters Patent should have been issued to The Union Switch and Signal Company,

a corporation of Penney Mania, as assignee by mesne asscgnments, as shown by the records of assignments in this office; and that the said Letters Patent should be read with this correction thereinthat the same may conform to the record of the case J. T. NEWTON,

7 Acting Commissioner of Patents.

owner of said invention, whereas said 

